Quantifying the Effect of Transportation Infrastructure Deterioration on Travelers' Economic Welfare

Engineers use an array of yardsticks, ranging from visual inspection to physical measurements, occasionally combined with users' costs assessed from average long-term traffic data, to characterize a transportation facility's condition and prioritize maintenance needs. This approach is inconsistent with basic economics principles that recognize that transportation facility users optimize their well-being by making rational decisions regarding travel choices. This paper outlines a joint engineering-economic modeling framework that converts engineering indicators of facility condition to a measure of consumer welfare. The feasibility of this framework is demonstrated by applying it to a case study that assesses the welfare of users of a network composed of two substitutable bridges with deteriorating riding surfaces. The analysis accounts for increased users' costs as well as the reduction in traffic volume on a deteriorating facility due to partial diversion of its traffic to the alternate facility. Such joint engineering-economic analyses would give better appreciation of the economic impact of facility deterioration and maintenance deferrals, eventually leading to more informed maintenance decisions compared with those that rely solely on traditional engineering criteria.